1. Field of the Invention
The present invention relates generally to devices powered by energy generated by impacts and, more particularly, to consumer devices, such as a flashlight powered by an impact.
2. Prior Art
In general, all chemical batteries contain hazardous and/or corrosive chemicals, have a relatively short shelf life, are relatively expensive and introduce waste disposal problems, with the latter being particularly the case for lithium based batteries and most rechargeable batteries. To satisfy the need for alternative power source solutions for various devices in general and for flashlights in particular, products have been developed that utilize coil and magnets to generate electrical energy. Bicycle dynamo and cranking type of dynamos have long been used to generate electrical energy. Similar coil and magnet generators have also been used in flashlights in the form of rotary crank type and sliding shaking type generators. The crank type generators are relatively heavy and bulky and when designed to be small as is needed for flashlights, they are cumbersome and tiring to crank. The shake type linear motion generators generate very small amounts of electrical energy during each shaking cycle, and are also relatively heavy. Each of such cranking and shaking devices are limited by the physical ability of the person providing the energy to crank or shake the device. In addition, the availability of low cost LED (Light Emitting Diode) lights that consume significantly less electrical energy than conventional light bulbs have made flashlights that harvest energy from the environment, including the user induced actions, much more practical. This is particularly the case for flashlights that are to be used in emergency situations and/or for use in locations where electricity is not available such as in the beach, during hiking, and the like, where flashlights with rechargeable batteries are not practical.
The only source of energy that is available to humans that could be harvested is mechanical energy. The energy to be harvested by any energy harvesting power source is mechanical in nature. The difference between any such energy harvesting power sources is: 1) in the method of transferring mechanical energy to the energy harvesting device; and 2) in the method of transforming mechanical energy to electrical energy.
A superior method of transferring mechanical energy to the energy harvesting device is ergonomic and does not put undue stress on the user limbs and joints. The method must also be efficient in making available the work done by the human subject to mechanical energy that can be harvested. In addition, the transferred mechanical energy is preferably stored in an intermediate medium to lengthen the period of time available for its conversion to electrical energy since it is generally easier and more efficient to convert mechanical energy to electrical energy and store it in electrical storage devices such as capacitors and rechargeable batteries. The means of transforming mechanical energy to electrical energy is also desired to produce high enough voltage to make the process of charging rechargeable batteries and/or capacitors more efficient.
A need therefore exists for methods and related devices for efficient transfer of the work done by human muscles to mechanical energy that can be harvested efficiently and transformed into electrical energy.